This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This proposal requests CPU time on TeraGrid resources for research aimed at understanding the assembly of viral proteins to form capsids. The projects will examine the mechanisms of conformational transitions required for capsid formation in the proteins of two icosahedral viruses, and will study the association/dissociation of HIV capsid proteins. The simulations will use NAMD to simulate proteins in explicit water. Because conformational transitions and association events are not accessible to straightforward molecular dynamics simulations, the simulations will use recently developed path sampling methodologies to focus simulation time on the transitions. The proposed work is funded by the NIH NIAID (Award No. R01AI080791).